Gerhard and Marta Each Set a New Year's Goal to Lose

Gerhard and Marta each set a New Year's goal to lose 20% of their body weight by June. They both bought six-month memberships to a gym. Gerhard lost 25% of his body weight in the first four months, but he kept working out at the gym since he had paid for six months of membership. By June, Marta had lost only 10% of her body weight and was frustrated that she had failed to reach her goal. Marta is an example of

A) the sunk cost fallacy, since she paid for a membership but did not achieve her goal.
B) a framing bias, since the gym convinces people that they will reach a goal.
C) overconfidence because she did not realize how hard it would be to achieve a such an aggressive goal.
D) overvaluing the present relative to the future because she was not thinking of the progress she had made.